Element-specific channels for the photoexcitation of V-doped TiO2 nanoparticles

Incorporation of dopants in semiconductors is commonly used to modify the optical response and improve the efficiency of related devices. A physical understanding with elemental and local sensitivity of the electron excitation and trapping channels which follow photoexcitation is a prerequisite for knowledge-based materials design. By using high-resolution x-ray absorption methods we show that, in V-doped TiO2 nanoparticles, subband-gap visible light absorption is predominantly due to excitation of electrons from V ions to defective and long-lived Ti sites. We thus identify an element-specific photoexcitation channel.